Water treatment in at least one membrane filtration unit for assisted recovery of hydrocarbons

Abstract

A water treatment method is provided. The method includes filtering water in a membrane filtration unit including at least one membrane filtration module, collecting a permeate and collecting a retentate at the outlet of the membrane filtration module, withdrawing solid materials and/or hydrocarbons contained in the retentate, in order to provide a treated retentate, recycling the treated retentate at the inlet of the membrane filtration module, and providing a treated water flow from the permeate from membrane filtration module(s). An installation adapted for applying this method is also provided.

The invention claimed is: 
     
       1. A water treatment method, comprising the following successive steps:
 (i) filtering water in a membrane filtration unit comprising at least one membrane filtration module, the water containing hydrocarbons in an amount of up to 1000 ppm and suspended solid materials in an amount of up to 200 mg/L; 
 (ii) collecting a permeate and collecting a retentate at an outlet of the membrane filtration module(s); 
 (iii) withdrawing at least one of: (a) solid material and (b) hydrocarbons, contained in the retentate collected after step (ii) in order to provide a treated retentate; 
 (iv) recycling the treated retentate at the inlet of the membrane filtration module(s); and 
 (v) providing a treated water flow from the permeate of the membrane filtration module(s), the treated water flow comprising less than 10 ppm of hydrocarbons and less than 10 mg/L of suspended solid materials, 
 wherein the membrane filtration unit includes inorganic membrane filters in ceramic based Al 2 O 2 , TiO 2 , ZrO 2 , SiO 2 , MgO, SiC or a mixture thereof, having a pore size ranging from 0.01 to 10 μm. 
 
     
     
       2. The method according to  claim 1 , further comprising withdrawing the water feeding the membrane filtration unit from at least one of: (a) the environment and (b) production water from a production flow extracted in an underground formation containing hydrocarbons. 
     
     
       3. The method according to  claim 2 , comprising at least one of:
 (a) pre-treating the production water prior to the filtration of the latter, the pre-treatment comprising at least one step selected from gas/liquid separation, liquid/solid separation and water/hydrocarbons separation; and 
 (b) pre-treating the withdrawn water prior to the filtration of the latter, the pre-treatment comprising at least one step selected from preliminary filtration, deoxygenation, chlorination, desulfatation, biocidal treatment and injection of anti-deposition or anti-corrosion compounds. 
 
     
     
       4. The method according to  claim 1 , further comprising purification of the treated water flow in an additional membrane filtration unit, and collecting a flow of treated and purified water from the additional membrane filtration unit. 
     
     
       5. The method according to  claim 1 , further comprising locating the membrane filtration unit at sea on one of: (a) a floating support or (b) a sea bed. 
     
     
       6. The method according to  claim 1 , further comprising injecting the flow of treated and if necessary purified water into an underground formation containing hydrocarbons. 
     
     
       7. The method according to  claim 6 ; further comprising, before the step of injecting, adding at least one additive into the flow of treated and if necessary purified water. 
     
     
       8. The method according to  claim 1 , wherein the membrane filtration unit comprises more than one membrane filtration module, and wherein the membrane filtration modules are positioned in series. 
     
     
       9. The method according to  claim 1 , wherein the membrane filtration unit comprises more than one membrane filtration module, and wherein the membrane filtration modules are positioned in parallel. 
     
     
       10. A method for producing hydrocarbons comprising:
 (i) filtering water with at least one membrane filtration module including an inlet and an outlet, the water containing hydrocarbons in an amount of up to 1000 ppm and suspended solid materials in an amount of up to 200 mg/L; 
 (ii) collecting a permeate and collecting a retentate at the outlet of the at least one membrane filtration module; 
 (iii) withdrawing at least one of: (a) solid material and (b) hydrocarbons, contained in the retentate collected after step (ii) in order to provide a treated retentate; 
 (iv) recycling the treated retentate at the inlet of the at least one membrane filtration module; and 
 (v) providing a treated water flow from the permeate of the at least one membrane filtration module, the treated water flow comprising less than 10 ppm of hydrocarbons and less than 10 mg/L of suspended solid materials; 
 (vi) injecting the flow of treated and if necessary purified water into an underground formation containing hydrocarbons; and 
 (vii) recovering a flow of the hydrocarbons from a production flow. 
 
     
     
       11. A water treatment installation, comprising:
 (a) a membrane filtration unit comprising:
 at least one membrane filtration module; 
 a water admission line connected at the inlet of the membrane filtration module(s); 
 a line for collecting permeate connected at the outlet of the membrane filtration module(s); 
 a retentate collector connected at the outlet of the membrane filtration module(s); 
 a separator operably separating at least one of: liquid/solid or water/hydrocarbons, the separator being fed only by the retentate collector; 
 a line for recycling the treated retentate, connected at the outlet of the separator and feeding the water admission line; and 
 
 (b) a line for collecting treated water from the membrane filtration unit, 
 wherein the membrane filtration unit includes inorganic membrane filters in ceramic based Al 2 O 2 , TiO 2 , ZrO 2 , SiO 2 , MgO, SiC or a mixture thereof, having a pore size ranging from 0.01 to 10 μm. 
 
     
     
       12. The installation according to  claim 11 , wherein the separator further comprises a hydrocyclone. 
     
     
       13. The installation according to  claim 11 , further comprising:
 a pump for withdrawing water from the environment; 
 a unit for extracting hydrocarbons contained in an underground formation; 
 a line for admitting withdrawn water stemming from the pump and feeding the membrane filtration unit; and 
 a production water admission line fed by the hydrocarbon extraction unit and feeding the membrane filtration unit. 
 
     
     
       14. The installation according to  claim 13 , comprising at least one of:
 (a) a first pre-treatment unit located on the production water admission line, the first pre-treatment unit comprising at least one separation system selected from gas/liquid separation systems, liquid/solid separation systems and water/hydrocarbons separation systems; and 
 (b) a second pre-treatment unit located on the withdrawn water admission line, the second pre-treatment unit comprising at least one piece of equipment selected from a preliminary filtration system, a deoxygenation system, a chlorination system, a desulfatation system, a biocidal treatment system and a system for injecting anti-deposition or anti-corrosion compounds. 
 
     
     
       15. The installation according to  claim 11 , wherein the membrane filtration unit comprises a plurality of membrane filtration trains, each membrane filtration train comprising a feeding pump and at least one circuit which each comprise at least one membrane filtration module, and a distribution system fed by the withdrawn water admission line and the production water admission line and feeding the membrane filtration trains. 
     
     
       16. The installation according to  claim 11 , comprising:
 an additional membrane filtration unit fed by the treated water collecting line; and 
 a line for collecting treated and purified water connected at the outlet of the additional membrane filtration unit. 
 
     
     
       17. The installation according to  claim 11 , wherein the unit is positioned on one of: (a) a floating support at sea or (b) the sea bed. 
     
     
       18. The installation according to  claim 11  wherein the membrane filtration unit comprises more than one membrane filtration module, and wherein the membrane filtration modules are positioned in series. 
     
     
       19. The installation according to  claim 11 , wherein the membrane filtration unit comprises more than one membrane filtration module, and wherein the membrane filtration modules are positioned in parallel.